Knowing UAN No Using PAN Or Aadhar Card - Employer Perspective

Dear seniors,
I have a query in regards to the new unified EPFO system.
In the new EPFO system can the present employer know the previous UAN number of a new employee using PAN or Aadhar details if the employee doesn't disclose the same in the form 11?
I know if the employee gives wrong declaration and asks the employer to generate a new UAN as if haven't had a UAN earlier the new employer will go ahead and while generating the new UAN the moment he puts the PAN or Aadhar details of the employee he'll get an error saying "previous employment exists". But my question is can he know the member id or UAN no of the previous employment using the PAN or Aadhar details or he has to ask the employee to give the same?

keep blank the UAN and previous employment ID no
then fill the details, name, DOB, aadhar pan and submit
it will display the data

Thank you. I didn't know that.
For new member registration in kyc section Aadhar is not working properly. Aadhar updation as new kyc gives some kind of error.
Is this happening with everyone or we are the one facing this problem?
And since you are veteran in this field would like to know one more thing from you - one employee in Indore joined and confirmed that he didn't have UAN in form 11. Now we have found out that he had UAN earlier.
Should we go ahead with form 11 and generate a new UAN for him or link it with his previous UAN that we have found out in his pay slips.
Should we adhere to form 11 or we should go by what we have found out in UAN website and in his pay slips?

to be specific to the query
since last june department flashed a notice to add members exact as per aadhaar data, name , relation name, DOB all must match the aadhaar data, hope everyone has noticed the same
department had asked the employers to seed their aadhaar latest by 15 dec 2016 and verify the same digitally, in that case minor variations under name, date etc would got approved and it is under scurtiny, some of them would get rejected , and they would have to reload it with rectified aadhaar
but aat present, everything MUST match the UAN data, viz, name, relation name, date of birth, as per UAN portal and aadhaar data porth both must reconcile each other, otherwise it would get rejected.
mere year of birth is not enough now to seed or generate UAN, it will ask now letter by letter match otherwise rejected